coinfection
Coinfection is the simultaneous infection of a host by multiple pathogen species. In virology, coinfection includes simultaneous infection of a single cell by two or more virus particles. An example is the coinfection of liver cells with h ...
of a host cell with a
helper virus
A helper virus is a virus that allows an otherwise-deficient coinfecting virus to replicate. These can be naturally occurring as with Hepatitis D virus, which requires Hepatitis B virus to coinfect cells in order to replicate. Helper viruses are a ...
for its replication. Satellites can be divided into two major classes: satellite viruses and satellite nucleic acids. Satellite viruses, which are most commonly associated with plants, are also found in mammals, arthropods, and bacteria. They encode structural proteins to enclose their genetic material, which are therefore distinct from the structural proteins of their helper viruses. Satellite
nucleic acid
Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main cl ...
s, in contrast, do not encode their own structural proteins, but instead are encapsulated by proteins encoded by their helper viruses. The genomes of satellites range upward from 359 nucleotides in length for satellite tobacco ringspot virus RNA (STobRV).
Most viruses have the capability to use host enzymes or their own replication machinery to independently replicate their own viral RNA. Satellites, in contrast, are completely dependent on a
helper virus
A helper virus is a virus that allows an otherwise-deficient coinfecting virus to replicate. These can be naturally occurring as with Hepatitis D virus, which requires Hepatitis B virus to coinfect cells in order to replicate. Helper viruses are a ...
for replication. The symbiotic relationship between a satellite and a helper virus to catalyze the replication of a satellite genome is also dependent on the host to provide components like replicases to carry out replication.
A satellite virus of mamavirus that inhibits the replication of its host has been termed a
virophage
Virophages are small, double-stranded DNA viral phages that require the Coinfection, co-infection of another virus. The co-infecting viruses are typically giant viruses. Virophages rely on the viral replication factory of the co-infecting giant ...
. However, the usage of this term remains controversial due to the lack of fundamental differences between virophages and classical satellite viruses.
History and discovery
The
tobacco necrosis virus
''Tobacco necrosis virus A'' is a plant pathogenic virus of the family ''Tombusviridae''.
Hosts and symptoms
Tobacco necrosis virus (TNV) can thrive on a handful of viable hosts. These hosts include tobacco, zucchini, cucumbers, carrots, French ...
was the virus that led to the discovery of the first satellite virus in 1962. Scientists discovered that the first satellite had the components to make its own protein shell. A few years later in 1969, scientists discovered another symbiotic relationship with the tobacco ringspot neopvirus (TobRV) and another satellite virus. The emergence of satellite RNA is said to have come from either the genome of the host or its co-infecting agents, and any vectors leading to transmission.
A satellite virus important to human health that demonstrates the need for co-infection to replicate and infect within a host is the virus that causes hepatitis D. Hepatitis D or delta virus (HDV) was discovered in 1977 by
Mario Rizzetto
Mario Rizzetto (born 4 June 1945) is an Italian virologist who in 1977 first reported the Hepatitis D virus as a nuclear antigen in patients infected with HBV who had severe liver disease.
He graduated in Medicine and Surgery at the University ...
and is differentiated from hepatitis A, B, and C because it requires viral particles from hepatitis B virus (HBV) to replicate and infect liver cells. HBV provides a surface antigen, HBsAg, which is utilized by HDV to create a super-infection resulting in liver failure. HDV is found all over the globe but is most prevalent in Africa, the Middle East and southern Italy.
Satellite compared to a virus
Classification
The classification of subviral agents is ongoing. The following uses an outline for subviral agents in a 2011 ICTV report. newer version; does not mention satellites A lot of the taxa have since been assigned more formal names in 2019, so these are included when possible.
Satellite viruses
Some satellite viruses have been assigned a taxon. The following reflects the results of a 2015 proposal that has since been accepted (Taxoprop 2015.009a).
*Single-stranded
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
Aumaivirus
Maize white line mosaic satellite virus (syn. Satellite maize white line mosaic virus, Satellite virus of maize white line mosaic virus, SMWLMV, SV-MWLMV) is a plant satellite virus. It is the only species in genus ''Aumaivirus'', which is a memb ...
Panicum mosaic satellite virus
Panicum mosaic satellite virus (SPMV) is a plant satellite virus in genus ''Papanivirus'', which is a member of realm ''Riboviria'' without assigned family or order. It only infects grasses which are infected by ''Panicum mosaic virus''. One stu ...
Organic Lake virophage
Organic Lake virophage (OLV) is a double-stranded DNA virophage (a virus that requires the presence of another virus to replicate itself and in so doing limits the ability of the other virus to replicate). It was detected metagenomically in sampl ...
The following may not be comprehensive in its ICTV coverage. The nomenclature for satellite RNAs is to prefix the host virus name with "sat".
Satellite-like nucleic acids resemble satellite nucleic acids, in that they replicate with the aid of helper viruses. However they differ in that they can encode functions that can contribute to the success of their helper viruses; while they are sometimes considered to be genomic elements of their helper viruses, they are not always found within their helper viruses.
*Single-stranded satellite DNAs
**Family
Alphasatellitidae
''Alphasatellites'' are a single-stranded DNA family of satellite viruses that depend on the presence of another virus (helper viruses) to replicate their genomes. As such, they have minimal genomes with very low genomic redundancy. The genome is ...
(encoding a replication initiator protein)
**Family
Tolecusatellitidae
''Tolecusatellitidae'' is a family of biological satellites that is not assigned to any higher taxonomic ranks. The family contains two genera and 131 species. This family of viruses depend on the presence of another virus ( helper viruses) to ...
Taxoprop 2016.021a-kP
*** Genus Betasatellites (encoding a pathogenicity determinant βC1)
*** Genus Deltasatellites (appears defective in βC1, but is their own group)
*Double-stranded satellite
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
s
**''
Saccharomyces cerevisiae M virus satellite
''Saccharomyces'' is a genus of fungi that includes many species of yeasts. ''Saccharomyces'' is from Greek σάκχαρον (sugar) and μύκης (fungus) and means ''sugar fungus''. Many members of this genus are considered very important ...
''
**''
Trichomonas vaginalis T1 virus satellite
''Trichomonas'' is a genus of anaerobic excavate parasites of vertebrates. It was first discovered by Alfred François Donné in 1836 when he found these parasites in the pus of a patient suffering from vaginitis, an inflammation of the vagi ...
''
*Single-stranded satellite RNAs
**Large linear satellite RNAs
***''
Arabis mosaic virus large satellite RNA
''Arabis'' ,''Sunset Western Garden Book,'' 1995:606–607 or rockcress, is a genus of flowering plants, within the family Brassicaceae.
Description
The species are herbaceous, annual or perennial plants, growing to 10–80 cm tall, ...
''
***''
Bamboo mosaic virus satellite RNA
Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, b ...
'' (satBaMV)
***''
Chicory yellow mottle virus large satellite RNA
Common chicory (''Cichorium intybus'') is a somewhat woody, perennial herbaceous plant of the family Asteraceae, usually with bright blue flowers, rarely white or pink. Native to the Old World, it has been introduced to North America and Austral ...
''
***''
Grapevine Bulgarian latent virus satellite RNA
''Vitis'' (grapevine) is a genus of 79 accepted species of vining plants in the flowering plant family Vitaceae. The genus is made up of species predominantly from the Northern Hemisphere. It is economically important as the source of grapes, b ...
''
***''
Grapevine fanleaf virus satellite RNA
''Vitis'' (grapevine) is a genus of 79 accepted species of vining plants in the flowering plant family Vitaceae. The genus is made up of species predominantly from the Northern Hemisphere. It is economically important as the source of grapes, b ...
Tomato black ring virus satellite RNA
The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word , ...
''
***''
Beet ringspot virus satellite RNA
The beetroot is the taproot portion of a beet plant, usually known in North America as beets while the vegetable is referred to as beetroot in British English, and also known as the table beet, garden beet, red beet, dinner beet or golden bee ...
''
***''
Beet necrotic yellow vein virus RNA5
The beetroot is the taproot portion of a beet plant, usually known in North America as beets while the vegetable is referred to as beetroot in British English, and also known as the table beet, garden beet, red beet, dinner beet or golden bee ...
Pea enation mosaic virus satellite RNA
The pea is most commonly the small spherical seed or the seed-pod of the flowering plant species ''Pisum sativum''. Each pod contains several peas, which can be green or yellow. Botanically, pea pods are fruit, since they contain seeds an ...
Panicum mosaic virus small satellite RNA
''Panicum'' (panicgrass) is a large genus of about 450 species of Poaceae, grasses native throughout the tropical regions of the world, with a few species extending into the northern temperate zone. They are often large, Annual plant, annual or P ...
Turnip crinkle virus satellite RNA
The turnip or white turnip (''Brassica rapa'' subsp. ''rapa'') is a root vegetable commonly grown in temperate climates worldwide for its white, fleshy taproot. The word ''turnip'' is a compound of ''turn'' as in turned/rounded on a lathe and '' ...
''
***''
Tomato bushy stunt virus satellite RNA, B10
The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word , ...
Tobacco bushy top virus satellite RNA
Tobacco is the common name of several plants in the genus ''Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ch ...
''
**Circular satellite RNAs or "
virusoid
Virusoids are circular single-stranded RNA(s) dependent on viruses for DNA replication, replication and encapsidation. The genome of virusoids consist of several hundred (200–400) nucleotides and does not code for any proteins.
Virusoids a ...
Tobacco ringspot virus satellite RNA
Tobacco is the common name of several plants in the genus ''Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ch ...
'' (satTRsV) above two forms a clade
***''
Chicory yellow mottle virus satellite RNA
Common chicory (''Cichorium intybus'') is a somewhat woody, perennial herbaceous plant of the family Asteraceae, usually with bright blue flowers, rarely white or pink. Native to the Old World, it has been introduced to North America and Austral ...
'' (satCYMoV)
***''
Solanum nodiflorum mottle virus satellite RNA
''Solanum'' is a large and diverse genus of flowering plants, which include three food crops of high economic importance: the potato, the tomato and the eggplant (aubergine, brinjal). It is the largest genus in the nightshade family Solanaceae ...
''
***''
Subterranean clover mottle virus satellite RNA
Subterranean(s) or The Subterranean(s) may refer to:
* Subterranea (geography), underground structures, both natural and man-made
Literature
* ''Subterranean'' (novel), a 1998 novel by James Rollins
* ''Subterranean Magazine'', an American fa ...
''
***''
Velvet tobacco mottle virus satellite RNA
Weave details visible on a purple-colored velvet fabric
Velvet is a type of woven tufted fabric in which the cut threads are evenly distributed, with a short pile, giving it a distinctive soft feel. By extension, the word ''velvety'' means ...
'' above four forms a clade
***''
Lucerne transient streak virus satellite RNA
Lucerne ( , ; High Alemannic: ''Lozärn'') or Luzern ()Other languages: gsw, Lozärn, label=Lucerne German; it, Lucerna ; rm, Lucerna . is a city in central Switzerland, in the German-speaking portion of the country. Lucerne is the capital of ...
'' (satLTSV)
***''
Cereal yellow dwarf virus-RPV satellite RNA
A cereal is any Poaceae, grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, Cereal germ, germ, and bran. Cereal Grain, grain crops are grown in greater quantit ...
''
***''
Cherry small circular viroid-like RNA
A cherry is the fruit of many plants of the genus ''Prunus'', and is a fleshy drupe (stone fruit).
Commercial cherries are obtained from cultivars of several species, such as the sweet ''Prunus avium'' and the sour '' Prunus cerasus''. The na ...
Kolmioviridae
''Ribozyviria'' is a Realm (virology), realm of Satellite (biology), satellite nucleic acids. Established in International Committee on Taxonomy of Viruses, ICTV TaxoProp 2020.012D, the realm is named after the presence of genomic and antigenomic ...
'' – ''Deltavirus''-like satellite-like RNAs
*** Genus '' Deltavirus'' –
Hepadnavirus
''Hepadnaviridae'' is a family of viruses. Humans, apes, and birds serve as natural hosts. There are currently 18 species in this family, divided among 5 genera. Its best-known member is hepatitis B virus. Diseases associated with this family i ...
-associated satellite-like RNAs
**
Polerovirus
''Polerovirus'' is a genus of viruses, in the family '' Solemoviridae''. Plants serve as natural hosts. There are 26 species in this genus. Diseases associated with this genus include: PLRV causes prominent rolling of the leaves of potato and a ...
Virusoid
Virusoids are circular single-stranded RNA(s) dependent on viruses for DNA replication, replication and encapsidation. The genome of virusoids consist of several hundred (200–400) nucleotides and does not code for any proteins.
Virusoids a ...
Virophage
Virophages are small, double-stranded DNA viral phages that require the Coinfection, co-infection of another virus. The co-infecting viruses are typically giant viruses. Virophages rely on the viral replication factory of the co-infecting giant ...